The Formation of Cyclic Ketones by Intramolecular Acylation

The cyclizations of gamma-phenylbutyric acid (I) to tetralone-1 (II) and of beta-phenylpropionic acid (III) to hydrindone-1 (IV) exemplify a type of intramolecular acylation which has served as an important tool in the synthesis of polycyclic hydroaromatic and aromatic compounds, Such ring closures have been effected by a variety of methods, generally involving either the direct cyclodehydration of the acids or the cyclodehydrohalogenation of the acid chlorides by an intramolecular Freidel-Crafts reaction. This chapter presents a discussion of these methods and the various problems involved in the formation of cyclic ketones by the ring closure of aryl-substituted aliphatic acid. Keywords: cyclic ketones; intramolecular acylation; ring size; steric factors; ring closures; benzene; naphthalene; phenathrene; cyclization